REFRIGERATION - 1

FUNDAMENTALS OF REFRIGERATION

Refrigeration is a general term. It describes the process of removing heat from spaces, objects, or materials and maintaining them at a temperature below that of the surrounding atmosphere. To produce a refrigeration effect, the material to be cooled needs only to be exposed to a colder object or environment. 

The heat will flow in its NATURAL direction-that is, from the warmer material to the colder material. Refrigeration, then, usually means an artificial way of lowering the temperature. Mechanical refrigeration is a mechanical system or apparatus that transfers heat from one substance to another.

THE  REFRIGERATION   TON

The unit of measure for the amount of heat removed is known as the refrigeration ton. The capacity of a refrigeration unit is usually stated in refrigeration tons. The refrigeration ton is based on the cooling effect of 1 ton (2,000 pounds) of ice at 32°F melting in 24 hours. The latent heat 

Latent (hidden) heat when added or removed changes the state of a substance with no change in temperature or pressure. Example, the heat added to water to boil it into a gas (steam) The temperature remains at 212°F throughout the process. 

of fusion of ice (or water) is 144 BTU's. Therefore, the number of BTU's required to melt 1 ton of ice is 144 x 2,000= 288,000. The standard refrigeration ton is defined as the transfer of 288,000 BTU's in 24 hours. On an hourly basis, the refrigeration ton is 12,000 BTU's per hour (288,000 divided by 24).

The refrigeration ton is the standard unit of measure used to designate the heat-removal capacity of a refrigeration unit. It is not a measure of the ice-making capacity of a machine, since the amount of ice that can be made depends on the initial temperature of the water and other factors.

MECHANICAL REFRIGERATION SYSTEMS

Various types of refrigerating systems are used for shipboard refrigeration and air conditioning. The one usually used for refrigeration purposes is the vapor compression cycle with reciprocating compressors.